Physiological and ultrastructural changes associated with petal abscission in 'Edouard' rose (Rosa bourboniana Desp.) and 'Red' rose (Rosa centifolia L.)
Two cultivars of roses viz., Edouard rose (Rosa bourboniana Desp.) and Red rose (Rosa centifolia L.) belong to the scented group of roses and are used in garland making and in the fragrance industry. The petal shedding nature of these two species remains a constraint for their large scale cultivation. A study was conducted on the physiological and ultrastructural changes associated with petal abscission in these two cultivars of Rosa spp. The study revealed that an increased activity of enzymes such as IAA oxidase (3162.7 and 2761.7 μg of unoxidised auxin g-1 h-1) and peroxidase (13.90 and 12.20 change in absorbance at 420 nm g-1 h-1), an increased evolution of ethylene (3.14 ppm kg-1 h-1 and nil evolution) and a decline in respiratory activity (174.80 and 214.05 ppm CO2 g-1 h-1) between these two cultivars, respectively. Microtoming of the pedicel and receptacle of the flower buds was done to observe the cell level changes changes taking place during abscission of flower petals. Cross section of pedicel and receptacle of flower buds were taken at different stages of flower development such as, on the emerging bud, unopened mature bud, freshly opened flower and senescing flower. In the flower pedicel of Edouard rose, on the day of abscission, changes such as invagination of cell walls and cell wall break down were noted in the vascular bundles while in Red rose, these changes were notable only on the third day of flower opening. Further, on the day of abscission, in the receptacle of Edouard rose flowers, increase in cellular space and cell wall collapse were observed in the parenchyma cells of the cortex and between the vascular bundle and epidermis while such changes were not evident in Red rose. The ultrastructural changes were more pronounced in Edouard rose (R. bourboniana) when compared to Red rose (R. centifolia)..
Thamaraiselvi, S.P., Kennedy, J.F., Ganga, M. and Anitha, K. (2019). Physiological and ultrastructural changes associated with petal abscission in 'Edouard' rose (Rosa bourboniana Desp.) and 'Red' rose (Rosa centifolia L.). Acta Hortic. 1241, 269-274
enzyme activity, microtoming, petals, 'Edouard' rose, 'Red' rose, petal abscission